The invention relates to an ergometer having an eddy current brake which serves as a loading device. The eddy current brake includes a rotatably mounted brake wheel which can be made to rotate by a drive means and has a cylindrical ring of an electrically conductive material as well as a stationary magnet system having poles directed toward the ring. Between the poles and the ring an air gap is present.
In a known ergometer of this type the magnet system is arranged within the cylindrical ring of the brake wheel, so that the flux produced by the magnet system enters into the inner cover surface of the ring and also exits therefrom. Because the ring is heated during operation as a result of the eddy current losses produced therein, and therefore expands, during operation the air gap becomes enlarged. This leads to a decrease in the magnetic flux and thus to a decrease in the brake load. An increase in the temperature of the ring has the same effect. In order to be able to keep the brake load constant, the energizing current to the magnet system must be increased as the temperature rises. The electronic apparatus required for this purpose clearly has an effect on the manufacturing costs of the ergometer.